How many jack posts to use to lower one joist?

I have an odd situation here where my floor has a bow in it about 5 feet inside the front door.

A structural engineer came out to look at my foundation wall, noticed the bow in my living room floor, then immediately noticed the cause and gave me the solution. The front foundation wall is oddly under the living room about 5-10 feet inside the front door. It goes the direction of the joists. The cement wall was only built about 4 feet or so, and then they just ran 2x4's up to the joist above, and put plywood on either side. The 2x4's are simply there to hold the plywood, which is there just to create a wall from outside (which is actually under the front door and front porch.

So, the structural engineer said that the house has been settling over the past 101 years, except that one joist hasn't settled as much because it's held up by these 2x4's on the short foundation wall.
She said I can simply cut them out and put new ones in there that are shorter to don't hold up the joist, and then simply rebuild a plywood wall to protect from outside.
So, my question is how many jack posts you'd recommend if I'm just using them for 1 joist (about 20-25ft long)? Again, she said that structurally I could just cut these 2x4's but that it would be better to lower the joist slowly with jacks after cutting the 2x4s out. So, I think the weight it fairly minimal. Would 2 jacks seem sufficient?

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How many jack posts to use to lower one joist?

OK, thanks for the tip. I'll look into that. The ones I was looking at are only $20, and I figure it may be a slow process to lower the joist completely (not sure how long yet). so i figured $40 was worth it. But I will look into what you mention.
Thanks again

How many jack posts to use to lower one joist?

Quote:

Originally Posted by 99miles

...... but that it would be better to lower the joist slowly with jacks .......

99, The Jack Posts that you found are designed to support weight, NOT raise or lower any significant weight, to do that you need is a Screw Jack. With a Screw Jack you insert a 2' to 4' long Turning Bar in the Jack to get enough leverage to raise or lower a large weight.